The purposes of the study is to evaluate the effect of 40 mg of prevastatin administered once daily in dyslipidemic (LDH cholesterol concentration >130mg/dl , triglyceride concentration > 90th percentile for age and HDL cholesterol concentration < 35mg/dl despite dietary intervention) patients with respect to plasma total cholesterol, LDL cholesterol, VLDL cholesterol, HDL cholesterol, and triglycerides. It is a randomized, double blind, placebo-controlled, crossover trial with a 6 week dietary lead in period.